Proposed as synchronous motors with a low magnetic flux have been, for example, inverter control devices for controlling inverters for driving a Synchronous Reluctance Motor (SynRM). A synchronous reluctance motor is a synchronous motor that does not use a permanent magnet, and in which the difference between an inductance in the d-axis direction (direction in which the magnetic flux flows easily) and an inductance in the q-axis direction (direction in which the magnetic flux flows hardly) generates a reluctance torque that causes the rotor to rotate.
Proposed for inverter control devices controlling a synchronous reluctance motor have been, amongst others, a method of calculating a current phase angle from a current amplitude command, and a method of calculating a current amplitude command and a current phase angle from a torque command using a linear or a quadratic function.
Also proposed have been speed controls to generate a torque command by multiplying a dq-axes current command by a coefficient in accordance with a speed command.
However, in the above-mentioned inverters configured to drive a synchronous motor having a low magnetic flux, using a method that adopts an arithmetic expression or a map makes it difficult to accurately calculate a current amplitude command in accordance with the torque command, whereby the torque output from the motor may, in some cases, not be in accordance with the torque command.